Geo-Synchronous Orbit (GSO) wideband satellite communications has experienced significant growth over the last several years, providing sizable increases in coverage and connectivity across the globe. One of the key enabling technology for satellite communication is spectrum sharing between broadband GSO and NGSO systems by imposing strictly interference control between the emerging NGSO and existing GSO systems to ensure their co-existence. It is well-known that the primary challenge to higher frequency Ka-band communication satellite system is the high rain fades. One of effective methods to mitigate the rain fade is applying power control techniques where transmit power is dynamically adjusted based on the rain fade estimation. For the approach to effectively mitigate rain fade while meeting interference criteria as set by ITU, accurate estimation of rain fade is critical. Furthermore, when adjusting the transmit power it is prudent to avoid unnecessary power increase in order to minimize potential interference to other systems.
Existing wireless networks mostly utilize Received Signal Strength Indicator (RSSI) power measurement to estimate downlink (satellite to ground) rain fade. The method utilizes a constant wave (CW) signal chain that is transmitted from the satellite at a known power level. The CW signal is monitored and compared to an expected level corresponding to no rain fade. If the CW signal is lower than expected, rain fade is concluded to be the cause of any attenuation. Such method can also require the CW signal to have precise gain which is susceptible to temperature variation especially if radio equipment is located in outdoor environment. In addition, the accuracy of the approach could be adversely affected by the interference signal, resulting in measurement error. The power control schemes are not optimized from end-to-end performance perspective, hence often transmit higher power (hence more interference) without overall performance benefit in return. Based on the foregoing, there is a need for an approach that improves rain fade estimation to facilitate more accurate transmit power adjustments.